Thermochromatic device and thermochromatic display apparatus

Abstract

A thermochromatic device includes an insulating substrate, a color element, a heating element, a first electrode, and a second electrode. The color element is located on the insulating substrate and includes a reversible thermochromatic material. The heating element is located adjacent to the color element and includes a carbon nanotube structure. The first electrode and the second electrode are electrically connected to the heating element. A thermochromatic display apparatus using the thermochromatic device is also related.

What is claimed is: 
     
       1. A thermochromatic device, comprising:
 an insulating substrate having a top surface; 
 a color element, located on the top surface of the insulating substrate, comprising a reversible thermochromatic material; 
 a first heating element configured to supply heat pulses to heat the color element, wherein the first heating element is a carbon nanotube structure, and the carbon nanotube structure is a substantially pure structure of carbon nanotubes; and 
 a first electrode and a second electrode electrically connected to the first heating element. 
 
     
     
       2. The thermochromatic device of  claim 1 , wherein the color element and the first heating element are stacked on each other. 
     
     
       3. The thermochromatic device of  claim 2 , wherein the first heating element is located between the insulating substrate and the color element. 
     
     
       4. The thermochromatic device of  claim 2 , wherein the first heating element is located on the color element and the color element is located between the insulating substrate and the first heating element. 
     
     
       5. The thermochromatic device of  claim 1 , wherein the first heating element is spaced from the color element and is in contact with the first electrode and the second electrode, and the first heating element and the color element are configured to exchange heat primarily by radiation. 
     
     
       6. The thermochromatic device of  claim 1 , wherein the insulating substrate has a recess defined on the top surface, the color element is located in the recess and covered by the first heating element, the first heating element covers the recess, and the first electrode and the second electrode are located on the first heating element so that at least part of the first heating element is sandwiched between the insulating substrate and one of the first electrode and the second electrode. 
     
     
       7. The thermochromatic device of  claim 1 , wherein the reversible thermochromatic material has a color change temperature below 200° C. 
     
     
       8. The thermochromatic device of  claim 1 , wherein the reversible thermochromatic material comprises an inorganic reversible thermochromatic material; the inorganic reversible thermochromatic material comprises a material that is selected from the group consisting of silver iodide, silver complex, silver double salt, copper iodide, copper complex, copper double salt, mercury iodide, mercury complex, mercury double salt, cobalt salt, nickel salt, methenamine compound, vanadium (III) oxide, chromate, vanadate, and combinations thereof. 
     
     
       9. The thermochromatic device of  claim 1 , wherein the reversible thermochromatic material comprises an organic reversible thermochromatic material; the organic reversible thermochromatic material comprises a color fixative, a color developing agent, and a solvent. 
     
     
       10. The thermochromatic device of  claim 1 , wherein the reversible thermochromatic material comprises a thermotropic liquid crystal. 
     
     
       11. The thermochromatic device of  claim 1 , wherein the carbon nanotube structure comprises at least one carbon nanotube film. 
     
     
       12. The thermochromatic device of  claim 11 , wherein a heat capacity per unit area of the at least one carbon nanotube film is less than 2×10 −4  J/m 2 ·K. 
     
     
       13. The thermochromatic device of  claim 11 , wherein the at least one carbon nanotube film comprises a plurality of carbon nanotubes substantially oriented along a same direction that extends from the first electrode to the second electrode. 
     
     
       14. The thermochromatic device of  claim 13 , wherein the plurality of carbon nanotubes of the at least one carbon nanotube film are joined end-to-end by Van der Waals attractive force therebetween. 
     
     
       15. The thermochromatic device of  claim 1 , wherein the carbon nanotube structure comprises at least one carbon nanotube wire; and the at least one carbon nanotube wire is a twisted carbon nanotube wire or untwisted carbon nanotube wire. 
     
     
       16. A thermochromatic display apparatus, comprising:
 a plurality of thermochromatic devices arranged to form a pixel matrix, and each of the plurality of thermochromatic devices comprises:
 an insulating substrate having a top surface; 
 a color element, located on the top surface of the insulating substrate, comprising a reversible thermochromatic material; 
 a heating element configured to supply heat pulses to heat the color element, wherein the heating element is a carbon nanotube structure, and the carbon nanotube structure is a substantially pure structure of carbon nanotubes; and 
 a first electrode and a second electrode electrically connected to the heating element; 
 
 a driving circuit for controlling the plurality of thermochromatic devices; and 
 a plurality of lead wires configured to electrically connect the driving circuit and the plurality of thermochromatic devices. 
 
     
     
       17. The thermochromatic display apparatus of  claim 16 , wherein the color element is located between the insulating substrate and the first heating element. 
     
     
       18. The thermochromatic display apparatus of  claim 16 , wherein the heating element is spaced from the color element, and the heating element and the color element are configured to exchange heat primarily by radiation. 
     
     
       19. The thermochromatic display apparatus of  claim 16 , wherein the insulating substrate has a recess defined on the top surface, and the color element is located in the recess and covered by the heating element. 
     
     
       20. A thermochromatic device, comprising:
 an insulating substrate comprising a top surface; 
 a color element on the top surface of the insulating substrate, comprising a reversible thermochromatic material; 
 a first heating element comprising a carbon nanotube structure and a second heating element, wherein the first heating element and the second heating element are parallel to each other, the color element is sandwiched between the first heating element and the second heating element, and the first heating element and the second heating element are configured to supply heat pulses to the color element; and 
 a first electrode and a second electrode, each of the first electrode and the second electrode being electrically connected to both the first heating element and the second heating element.